The influence of temperature on the color of TiO2:Cr pigments

• Autor(a) principal: Vieira, Fagner Ticiano Gomes
• Data de Publicação: 2009
• Outros Autores: Melo, Danniely Silva, Lima, Severino Jackson Guedes de, Silva, Elson Longo da, Paskocimas, Carlos Alberto, Silva Júnior, Wilson, Souza, Antonio Gouveia de, Santos, Iêda Maria Garcia dos
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRN
• Texto Completo: https://repositorio.ufrn.br/handle/123456789/32075
• topic: Oxides D. Crystal structure D. Defects D. Color centers; Chemical synthesis; Crystal structure; Defects; Color centers

TiO2:Cr brown pigments were prepared via a polymeric precursor derived from the Pechini method. The pigments were analyzed by infrared spectroscopy, X-ray diffraction, ultraviolet–vis spectroscopy, and colorimetry. The increase of the calcination temperature from 700 to 1000 8C led to a decrease in the L* values, corresponding to darkening of the pigments. The pigments obtained in this work are darker than those produced by a solid-state reaction method reported before. The change in the pigment color is due to the anatase–rutile phase transition, which leads to a shift in the charge transfer bond (Ti4+$O2 ) due to a change in the crystal field around the chromophore ions. Moreover, the oxidation state of chromium was observed to change, and this also alters the color of the pigments